1. Field of the Invention
The present invention relates to a semiconductor integrated circuit, a mobile module, and a message communication method.
2. Description of the Related Art
Semiconductor integrated circuits having a communication function to communicate with an external apparatus in a contact state have been developed. IC (integrated circuit) cards containing such a semiconductor integrated circuit are typically used as credit cards in business fields. Other types of developed integrated circuits can communicate with an external apparatus in a contactless manner or in a state in which the circuit and the external apparatus are physically in contact with each other but with no direct electrical connection established. An IC card containing such a semiconductor integrated circuit is typically used in station ticket gates.
Recently-developed dual-interface, IC cards having contactless and contact communication functions permit selectively the contactless communication and the contact communication with the external apparatus, as disclosed in Japanese Unexamined Patent Application Publication No. 2003-168092. Such an IC card complies with transmission protocols specified in International Standard ISO/IEC7816-3 for contact communications and International Standard ISO/IEC14443-4 for contactless communications. Although the transmission protocols are different from the contact communication and the contactless communication, the IC card stores command information in a volatile memory to be referenced by a system program or a plurality of application programs of the IC card when the IC card receives a command. The IC card thus receives the protocol difference so that the received command is reliably performed regardless of which protocol is received.
Although the transmission protocol is different from the contact communication to the contactless communication, the command to be transferred from the external apparatus to the IC card is standardized in International Standard ISO/IEC7816-4 and is common to both the contact communication and the contactless communication. In other words, the IC card is based on the assumption that the contact communication standard and the contactless communication standard are identical to each other in the structure of messages including command messages and response messages exchanged between the external apparatus and the IC card. If the message structure is different from the contact communication to the contactless communication, the IC is unable to process each other's messages.